The invention refers to an apparatus for cropping the head and tail ends of rolling material running at high speed, e.g., wire still warm from rolling. Modern wire rolling mills are today capable of rolling fine dimensions with discharge velocities of more than 50 m/sec. Wire blocks for velocities of 75 m/sec. or more are being constructed and designed. Cropping of the wire can be performed at the bundle as well as in the rolling line following the finishing train.
In the coiling station or after, the wire speed is low, but the coils are very close together. Automatic cutting can only be done with great variations in length. Optimum conditions afford a tolerance of one coil of roughly 3 m. In practical application, however, cutting inaccuracies of +2 coils (or nearly +4 coils, as minus tolerance is not permissible) must be calculated with, which means that at the front end and rear end the loss per bundle may be longer than the required minimum length of the end by 8 coils or roughly 24 m.
In the line following the finishing train, wire speeds are very high. However, each wire runs separately. With suitable shears the length of the end can be maintained more accurately. Also, removal and chopping of the ends is simplified. Shears as known heretofore, however, did not permit safe operation and relatively disturbance-free cutting at velocities exceeding 40 m/sec. The shears according to prior art which are used in the lines after finishing trains, were limited in their capacity due to the setting period required to bring the cutting blades into cutting position and to return them from the latter. The considerable acceleration and deceleration of the mass of blades to be moved, and of the displacement devices in revolving shears could not be controlled at such high speeds, so that such rotating shears could not be employed. In practical application, therefore, cutting is done on the line automatically as long as the shears run somewhat free of disturbances. At high rolling speeds, front and rear are cut by hand at the bundle station or at the hook track, or the wire is sold without ends being cut at respective losses, or the relatively great tolerances of bar head or bar end are accepted.
Another problem is the separation of divided rolling material following the shears onto different guide tracks such as, for example, towards the reel or towards scrap. The high rolling speeds demand switches for the rolling material, such switches being capable of guiding the rolling material strands arriving successively and divided by the shears quickly from one direction to another. Known switches of this type are not fast enough to allow for a change-over at very high rolling speeds after passage of the rear end of one strand and before entering of the front end of the following strand. It is, indeed, known to effect switching to another track for the next strand while the previous strand going to another track is still passing through, but to this end it is necessary to design the switch in such a way that the strand still running through the switch after change-over is not subject to excessive deflection. Measures must be taken to sheer the newly arriving strand head reliably to the new direction without having uncontrollable lateral swinging or a whip effect of the previously passing strand end.
A third problem presents itself in that the head and tail ends of the roller material usually cannot be used for further processing as they show various deviations from the required material quality, such as cross sectional flaws and over-rolling. It is known and common to sever the so-called crop ends and remove them from the rolling line. It is also known to divide such crop ends, which may be of considerable length, into short pieces to facilitate subsequent transportation and further processing.
In order to remove the crop ends from the rolling line, switches or the like are used which are arranged directly following the separating device. In order to create a space between crop piece and the rolling material strand permitting deflection of the crop piece from the rolling line, it is also known to provide so-called driving devices following the deflection device. The actual division of the crop ends is done by so-called choppers consisting, as a rule, of two drums or shafts which are provided at least at the circumference of one drum with isolated blades to chop up the rolling material passing between the drums. The driving devices arranged before the chopper consist, usually, also of two revolving drums whose peripheral velocity is somewhat greater than the passing velocity of the rolling material strand through the separating device. The rolling material is pulled away from between the drums of the driving device due to friction, whereby the drums of the driving device can be set in relation to the rolling material.
These arrangements have the disadvantage that the driving device and the chopper must be synchronized in such a way that material does not stagnate between the two, while on the other hand no excessive pull exists. In the first case, stagnated material would have considerable effects on the entire plant, extending all the way to the mill pass line. Secondly, excessive pull would tear the rolling material, and thus also lead to disturbance. The required synchronization of drives, regardless whether mechanical or electrical, is at any rate involved and expensive.
Another problem is the assessing of rolling material speed to adjust the peripheral speed of the rotary shears. It has been found that with the usual speed test by assessing the number of revolutions at the last rolling stand does not represent the actual velocity data of the rolling material passing through. Wear of the rollers and other factors of operation, which are not easily determined, permit slippage between rolling material and rollers so that the test data are no longer correct.
Based on the above problems it is the object of this invention to provide an apparatus to crop the head and tail ends of rolling material running at high speed, making it possible with the least structural means and a minimum of susceptibility to disturbance to safely handle the rolling material at very high speeds, to obtain clean and exact cutting of the wire strand, and to handle the distribution of the rolling material to continuing tracks at these high speeds without any disturbances. The apparatus contains means to remove the crop ends taken from the rolling line, such ends being reduced to chargeable pieces of scrap material. All parts of the apparatus lend themselves to adjusting and synchronizing to make possible an undisturbed operation of the entire plant at high velocities.
To solve this task, an apparatus of the initially described type is proposed which has the following combination of features:
(a) The rolling line following the finishing train is provided with rotary shears whose material guide drums, revolving at approximately the speed of rolling, are equipped with displaceable blades with are moved out of their inactive position within the drum to their cutting position. Servo-hydraulically controlled piston-cylinder units with succeeding servo-valves are provided as displacement drives for the blades, revolving with the latter and also arranged in the drums. PA0 (b) The shears are followed by a power-operated switch before two or more continuing tubular guide tracks, with the guide tube of the switch consisting of flexibly connected straight tubes, whose outlet portion, along its longitudinal axis, swivels essentially around the intersection of the axes of the continuing guide tracks in the outlet area of such tube portion, to a position coaxial with the guide tracks, whereby the outlet side of the guide tube ends leaving a free space before the inlet openings of the diverging continuing guide tracks. PA0 (c) One of the continuing guide tracks is followed by a chopper drive consisting of two drums arranged on a level and revolving at higher peripheral speed than the passing speed of the wire, whereby the circumference of at least one of the drums is provided with stationary blades to reduce the passing wire, and the space between the revolving drums is slightly smaller than the diameter of the passing wire. PA0 (d) The finishing train is followed by a laser speed test apparatus testing the rolling material speed, and from its test value and the true value of the speed, as taken from the last rolling stand of the finishing train, a difference is derived which is fed to the drive of the rotary shears as correction of the ideal value.
The combination of the proposed structural parts of the apparatus make it possible to crop, separate and reduce the crop ends, with rolling material on the line at any rolling speeds attained today. The structural parts required to this end may be installed with a minimum of space required. The chopper drive can be placed next to or below the rolling pass line. The integration of all structural parts into one compact plant and the proposed test data assessment and control of peripheral velocity of the rotary shears depending on the actual rolling material passing speed guarantees optimum utilization of individual steps of operation. The proposed apparatus to crop, separate and reduce rolling material running at high speed may be included in new installations, but can also be incorporated in quick and simple fashion in existing wire mills. The structural parts used are simple so that the manufacturing costs for such installations are very low. The overall result is a compact plant not susceptible to disturbance which solves the task given in an outstanding manner.
Another feature of the invention provides that one of the continuing guide tracks is followed by a second power-operated switch according to detail (b) in claim 1, which is in turn arranged before two or more continuing tubular guide tracks. This proposal makes it possible to feed the separated wire to two or more reels or other processing stations.